The present invention relates to an optical box for connecting optical fibres of a distribution cable to optical fibres of subscriber cables. The present invention also relates to a method of connecting at least one optical fibre of a distribution cable to at least one optical fibre of a subscriber cable.
High-capacity telecommunication cables are used in optical fibre telecommunication systems all the way to the user, known under the English acronym FTTH for “Fiber To The Home” or FTTC for “Fiber To The Curb”, and an individual access to each micromodule and/or each fibre is realized for a distribution into a particular building or a particular floor. In this context, by “distribution cable” is meant a telecommunication cable containing a plurality of fibres which are grouped in micromodules supplying an optical signal to a whole building or a group of buildings. The distribution cable can in particular be a vertical cable installed in the service shaft of a building or an external cable installed in urban conduits. The distribution cable can contain several tens of optical fibres. By “subscriber cable” is meant a cable containing one or more optical fibres connected to a subscriber box. A subscriber cable generally contains less than 10 optical fibres. A distribution box can supply a whole building, a whole floor or a particular apartment. The distribution cable is generally installed in a service shaft and the subscriber box is installed in each subscriber's premises, at some distance from the distribution cable. In order to connect the fibres of a subscriber cable to the fibres of the distribution cable, typically, a drop cable is used, from the distribution cable to a splicing box in which the bare fibres of the drop cable and of the subscriber cable are connected.
FIG. 1 diagrammatically illustrates an installation for dropping fibres from a distribution cable and connecting the dropped fibres to a subscriber box according to the prior art. Such an installation has in particular been presented by the company Prysmian® during the FTTH conference of the FTTH Council 2008 held in Paris on 27th and 28 Feb. 2008. Such an installation comprises a tapping box 10 fastened onto a distribution cable 100 supplying a whole building for example. The tapping box 10 makes it possible to cover and protect an opening made in the cable 100 by an operator for dropping at least one optical fibre. Generally, a first opening is made in the cable jacket and at least one fibre is cut through this first opening; then a second opening, termed tapping window, is made in the cable jacket and said cut fibre is drawn out in order to be dropped. The distance between the two openings depends on the applications. The tapping box 10 has a connection with a drop cable 120 which contains the dropped fibre(s) of the distribution cable 100. The installation of FIG. 1 also shows a splicing box 20 in which the drop cable 120 and a subscriber cable 150 emerge. The subscriber cable 150 is moreover connected to a subscriber box 30 in order to supply an optical signal to a particular subscriber. The splicing box 20 can receive a plurality of subscriber cables 150. For example, a whole floor of a building can be supplied by a single drop cable 120 from a vertical distribution cable 100 supplying the whole building; the splicing box 20 then allows a connection between the fibres of each subscriber cable 150 of this floor and the corresponding fibres of the drop cable 120.
The installation of FIG. 1 requires the use of two separate boxes, one for the dropping and the other for the splicing. The use of two separate boxes is often due to the fact that splicing is a delicate operation which requires the operator to work comfortably, while the dropping is generally carried out from a service shaft which is difficult to access. Nevertheless, the use of two boxes represents a cost and increases the number of operations during installation of an optical network in buildings. Furthermore, the increase in the number of boxes can detract from the decorative aesthetics of the building.
A need therefore exists for an optical box which makes it possible to combine the dropping and splicing of optical fibres, which is discreet and compact whilst allowing easy and efficient handling by the installation operator.